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Post subject: What exactly does a rectifier do?
Posted: Mon Nov 05, 2007 9:27 am
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I noticed that there are different types of rectifiers. The amp I am interested in has a solid state rectifier. What do they do and what are the differences? Thanks in advance for any info offered. All is appreciated.


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Posted: Mon Nov 05, 2007 9:51 am
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It's the Amps power supply.
Clicky

Basically it scales down and converts the 240V (or depending where you're from 110V) AC current from your socket into DC with a much lover voltage (ie. 25V), because you don't need all that energy just to power a bunch of tubes and speakers......if all that power did get in your amp would blow.

I'm not sure what the difference between the two types is though.


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Posted: Mon Nov 05, 2007 10:48 am
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Thank you much...


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Posted: Mon Nov 05, 2007 10:57 am
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Well, if you want to split hairs, the rectifier is only part of a conventional power supply - the part that converts AC to DC.
There's also a transformer before that to lower voltage (to 6 or 12 volts for the tube heaters) as well as raise voltage (most tube circuits need about a 300-400 volt supply for plate voltage). There's also a filter circuit to smooth the rectifier's output closer to pure DC.
A solid state rectifier should be a lot more reliable than a tube rectifier, and since all it does is change AC to DC, there's no audio benefit to a tube rectifier that I'm aware of. (If anyone has heard otherwise, please provide examples.)
I do have a question for anyone who knows: do any modern tube amps still use tube rectifiers?


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Posted: Fri Nov 09, 2007 2:55 pm
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Some modern tube amps do still use rectifiers, but not many.


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Post subject: Re: What exactly does a rectifier do?
Posted: Mon Nov 12, 2007 10:30 am
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Stratu812 wrote:
I noticed that there are different types of rectifiers. The amp I am interested in has a solid state rectifier. What do they do and what are the differences? Thanks in advance for any info offered. All is appreciated.


I'm no electrical tech, so I can't comment on the electrical components per se, but there is a difference (albeit subtle) in how the amp sounds if it's a solid state (diode) or tube rectifier.

It is first & formost the primary factor in my consideration of choosing an amp. Ideally all tube amps would give you this option, like the 64 Vibroverb Custom does, but I'm not aware of any others that do offer this choice.

If you read up on this after googling about it, you'll find the main word here is "sag". As you push a tube rectifier amp, the notes compress & sag because of the load on the tubes (I think), whereas a diode rectifier doesn't do this, but is rather harsh & cold, & a bit louder. A tube rectifier allows the notes to "breathe", somewhat. The signal doesn't actually pass through the rectifier, but is definitely affected by it.

It's old school to use tube rectifiers (heh, no choice back then), but those of us who are used to them wouldn't trade for diodes.

It absolutely baffles me that Fender doesn't offer this as a choice with all their tube amps, since it's one of the holy grails of tube ampology, & since Fender has been there since day one (although as a different owner then).


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